Super-turbochargers are convenient devices for increasing the power and/or efficiency of internal combustion engines. A smaller, more efficient engine that uses a super-turbocharger can produce the same power as a larger, less efficient engine, thereby improving the overall efficiency of the system. Super-turbochargers have at least one compressor and at least one turbine that are connected to a power transmission device that transmits power to and receives power from a propulsion train that is coupled to the engine, or to a crank shaft, vehicle transmission, or other coupling when the engine is used on a vehicle. In this manner, super-turbochargers can increase the performance of a piston engine, whether that engine is used on a vehicle, for power generation, or other function.